API: no_project filter + project_id on tasks route

- list_notes(): add no_project param → Note.project_id.is_(None) filter
- GET /api/notes: expose ?no_project=true
- GET /api/tasks: add ?project_id= and ?no_project=true pass-through

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/fabledassistant/routes/notes.py

@@ -61,6 +61,7 @@ async def list_notes_route():
     project_id = request.args.get("project_id", type=int)
     milestone_id = request.args.get("milestone_id", type=int)
     parent_id = request.args.get("parent_id", type=int)
+    no_project = request.args.get("no_project", "").lower() == "true"
 
     # type= shorthand used by web frontend (?type=task or ?type=note)
     type_param = request.args.get("type")
@@ -73,6 +74,7 @@ async def list_notes_route():
         uid, q=q, tags=tag or None, is_task=is_task, sort=sort, order=order,
         limit=limit, offset=offset,
         project_id=project_id, milestone_id=milestone_id, parent_id=parent_id,
+        no_project=no_project,
     )
     return jsonify({"notes": [n.to_dict() for n in notes], "total": total})